The method of shield tunneling with pressure entering the chamber with mud-killing effect

Abstract

The present invention provides a method for shield machine with pressure entering a warehouse with the aid of a mud-reducing effect. The method comprises the steps of calculation before entering the warehouse, preparation of film-building mud, water-stopping ring, replacement of slag with film-building mud, pressurization of film-building mud, retreat of the cutter head, replacement of film-building mud with gas, etc., wherein the film-building mud is a mud-reducing effect. The method for shield machine with pressure entering a warehouse with the aid of a mud-reducing effect provided by the present invention solves the problem that the existing mud film used for shield machine with pressure entering a warehouse is inconvenient and unsafe to use.

Description

Technical Field

[0001] The invention relates to the field of tunnel construction, and in particular to a method for a shield machine with mud-reducing effect to assist in entering a tunnel with pressure. Background Art

[0002] With the rapid development of urban subway construction in my country, the shield method has been widely adopted for its advantages of high efficiency, safety and environmental protection. However, during the shield tunneling construction, it is often necessary to open the warehouse to repair and replace the cutter and remove the mud cake. The shield opening operation has also become a major issue in shield construction. In the strata with abundant groundwater and poor stability of surrounding rock and soil, the opening operation often adopts the safer pressure opening to support the excavation surface with air pressure. However, since the pressure opening requires the production of mud film on the excavation surface to seal and seal the air, it provides the prerequisite for subsequent air pressure support. The traditional mud film is made of bentonite slurry as the main material, which is easily diluted by groundwater. The effects of different proportions in different strata vary greatly. Whether it is calcium-based bentonite or sodium-based bentonite, it takes a lot of time to expand before it can have membrane-building performance. If the mud film suddenly leaks, the excavation surface becomes unstable and new membrane-building mud cannot be produced immediately. At the least, the ground collapses, and at the worst, the tunnel will gush water and sand, which poses many construction risks. Summary of the invention

[0003] In order to solve the problem that the existing mud membrane used for shield belt pressure entry is inconvenient and unsafe to use, the present invention provides a mud-reducing effect auxiliary shield belt pressure entry method to solve the above problems.

[0004] A method for shield tunneling with pressure using a mud-killing effect, comprising the steps of calculation before entering the chamber, preparation of membrane-building mud, water-stop sealing ring, replacement of slag with membrane-building mud, pressurization of membrane-building mud, retreat of the cutterhead, and replacement of membrane-building mud with gas, characterized in that the membrane-building mud is a mud-killing effect.

[0005] In a preferred embodiment of the method for shield tunneling with pressure using a mud-reducing effect provided by the present invention, the calculation before entering the chamber includes determining the theoretical working pressure, which is the sum of the pressure of the geological conditions, ground environment and excavation face position and the water head pressure at the center of the tunnel excavation.

[0006] In a preferred embodiment of the method for assisting shield machine with pressure entry with mud-reducing effect provided by the present invention, a water-stop sealing ring is implemented at 3 to 7 ring segments behind the shield tail, and membrane-building mud is injected into the advance grouting holes, radial grouting holes and synchronous grouting holes of the shield machine body. The order of injecting the membrane-building mud is the bottom of the shield machine - the symmetrical waist - the top, forming a continuous water-stop ring.

[0007] In a preferred embodiment of the method for assisting shield tunneling with pressure entering a chamber with mud-reducing effect provided by the present invention, the membrane-building mud replaces the slag soil in two ways:

[0008] Option 1: Inject membrane-building slurry into the soil bin to replace the slag soil;

[0009] Option 2: Inject the intermediate medium into the soil bin to replace the slag soil; then inject the membrane-building mud into the soil bin to replace the intermediate medium.

[0010] When the membrane-building mud or the intermediate medium replaces the slag, the grouting is injected from the top through the reserved holes between the 10~2 points of the soil bin partition; when the membrane-building mud replaces the intermediate medium, the soil bin pressure is 0.1~0.2 bar higher than the pressure when the intermediate medium is injected into the soil bin.

[0011] In a preferred embodiment of the method for shield tunneling with pressure to enter a chamber with mud-reducing effect provided by the present invention, the membrane-building mud is pressurized by step-by-step pressurization. When the pressure is stable after the slag is replaced, the membrane-building mud is injected and step-by-step pressurization is directly performed.

[0012] The step-by-step pressurization takes 0.2 bar as one step, and the pressure is increased to 1.3~1.5 times of the working pressure entering the warehouse; each step of pressurization is continuously increased until the pressure is dynamically stable, and then the pressure is stabilized; during each step of pressurization, the cutter head of the shield machine is rotated half a circle at a low speed.

[0013] In a preferred embodiment of the method for advancing a shield machine under pressure with mud-reducing effect provided by the present invention, the cutterhead retreats by loosening the hinges or jacks of the shield machine when the pressure is applied in a step-by-step manner to the second-to-last stage, allowing the shield machine to retreat naturally under the action of pressure, and maintaining the pressure to inject membrane-building mud to fill the gap between the cutterhead of the shield machine and the excavation surface.

[0014] In a preferred embodiment of the method for assisting shield machine with pressure entry with mud-reducing effect provided by the present invention, gas replacement of membrane-building mud is implemented after the membrane-building mud forms a stable mud film on the excavation surface, including the steps of: opening the automatic pressure maintaining system of the sealed cabin, reducing the pressure to the working pressure after stabilizing the pressure for a period of time, discharging the membrane-building mud while replenishing air and maintaining the air pressure stable; and rotating the cutter head of the shield machine at a low speed while discharging the membrane-building mud.

[0015] Compared with the prior art, the present invention adopts the mud effect to replace the traditional mud film in the mud effect assisted shield belt pressure entry method, which can flexibly and accurately adjust the mud viscosity, and the mud film structure is dense and suitable for high permeability formations. It is not easy to be diluted by groundwater, and as an excavation surface mud film, it has water-proof properties and stable film formation.

[0016] The mud film has thixotropy. When the mud film needs to be pushed forward again after being solidified for a long time, the mud film can be stirred by rotating the cutter disc to restore its fluidity and meet the pumping conditions. It also has a certain strength and can easily carry out the slag blocks to avoid stagnation. The mud film can achieve its performance by mixing the two components A and B for tens of seconds. The mud film can be easily injected continuously through the dedicated grouting machine without pre-mixing, realizing the integration of stirring, mixing and injection, and the accurate metering and control of the ratio, which greatly improves the efficiency of slurry preparation and mud film production.

[0017] The present invention uses innovative methods such as mud effect sealing ring, multi-stage pressurization, and cutter head retreat to fully fill and squeeze the mud effect into the gap between the shield machine and the surrounding rock, blocking water and air leakage channels in all directions, thus breaking through the difficulty of shield machine operation under pressure in special unstable strata. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0019] Embodiment 1:

[0020] The method for advancing a shield machine with pressure under the aid of the mud-reduction effect comprises the following steps:

[0021] Step 1: Calculate before entering the warehouse.

[0022] The stratum with stable ground and no buildings or pipelines on the ground is selected as the location for pressure entry. The pressure adjustment value considering different geological conditions, ground environment and excavation face position, and the sum of the head pressure calculated to the center of tunnel excavation are used as the theoretical working pressure of the excavation chamber air pressure operation. According to the calculated theoretical working pressure, field experiments are carried out to ensure that the theoretical working pressure meets the stability of the excavation face.

[0023] Step 2: Prepare membrane-building slurry.

[0024] The membrane-building mud adopts the gram mud effect. It includes main materials and auxiliary materials. The main materials include 85-99% calcium carbonate and 1-15% calcified fiber; the auxiliary materials include 50-80% water and 20-50% additives. The additives include one or more of plasticizers, thickeners, stabilizers, dispersants, and waterproofing agents; the main materials are added with 30-50% water by mass and mixed with the auxiliary materials in a mass ratio of 3:1.

[0025] Step 3: Water-stop seal ring.

[0026] The scope of the water stop ring is 3 to 7 rings behind the shield tail. The mud effect is injected into the advance grouting holes, radial grouting holes and synchronous grouting holes of the shield machine in the order of the bottom of the shield machine-symmetrical waist-top, so that the mud effect evenly wraps the entire shield machine shell.

[0027] Step 4: Replace the slag with mud. There are two options:

[0028] Option 1: Inject the mud effect into the soil bin to replace the slag soil;

[0029] Option 2: Inject bentonite into the soil bin to replace the slag soil; then inject clay into the soil bin to replace the bentonite.

[0030] Before replacing the slag soil, the ground conditions should be investigated. For ground containing fine sand, medium-coarse sand and other ground that is prone to water loss and compaction, plan 2 should be used; for other situations, plan 1 should be used.

[0031] For Option 2, when injecting the clay effect into the soil bin to replace the bentonite, the soil bin pressure should be 0.2 bar higher than the pressure when the bentonite is injected into the soil bin.

[0032] Step 5: Pressurize the mud.

[0033] After the slag is replaced in step 4, when the pressure is stable, a double-liquid mixed injection is performed using a special mud-effect grouting equipment, and step-by-step pressurization is performed directly.

[0034] The step-by-step pressurization uses 0.2 bar as a pressurization step, and the pressure is increased to 1.5 times the working pressure of the warehouse. Taking the pressure of 1.6 bar after the slag replacement as an example, the first pressurization is to 1.8 bar, and the injection of sludge effect is stopped. The pressure change of the soil warehouse is observed. If the pressure drops to 1.6 bar, sludge effect is added to make the soil warehouse pressure dynamically stabilized at 1.8 bar and maintained for 2 hours. After that, at the two pressurization levels of 1.8~2.0 bar and 2.0~2.2 bar, the pressure is also dynamically stabilized for 2 hours by adding sludge effect. The final pressurization level of 2.2~2.4 bar is dynamically stabilized for 6 hours.

[0035] During the dynamic injection of mud effect at each pressurized stage, the cutter disc is rotated half a circle at a low speed (0.1r / min) to ensure the uniformity of mud effect injection and penetration.

[0036] Step 6: Move the knife disc backward.

[0037] When the step-by-step pressurization in step 5 reaches the second-to-last level, i.e., 2.0-2.2 bar, the shield machine hinge is loosened, and the reaction force of the injected mud effect pressure is used to make the shield machine naturally retreat 10 cm. The amount of mud effect injected is increased to fill the gap between the cutterhead and the excavation surface, forming a complete mud effect mud wall in front of the cutterhead.

[0038] Step 7: Gas displacement effect.

[0039] After a stable mud film is formed on the excavation surface, the automatic pressure-maintaining system of the sealed cabin is turned on and the pressure is maintained at the highest pressure for 6 hours. Then, natural pressure reduction is adopted first. After the natural pressure reduction stops, the pressure is reduced to the working pressure by air release. When the air supply volume meets the requirements of the specification and the air pressure is stable, the screw conveyor is used to discharge the mud effect to reduce the liquid level of the mud effect in the bin and make the soil bin have working space. During the pressure stabilization and pressure reduction process before discharging the mud effect, the cutter head is rotated at a low speed (0.1r / min) to maintain the fluidity of the mud effect slurry.

[0040] Step 8: Determine the conditions for entering the warehouse.

[0041] After replacing the gas with the mud effect, continue to open the automatic pressure-maintaining system until the working pressure in the warehouse can be stabilized and maintained for 6 hours, and the air compressor pressurization time is less than 10% of its standby time. Then it is judged that the mud film wall protection of the mud effect is completed, otherwise the mud film should be remade.

[0042] On-site engineers must conduct a comprehensive analysis and feedback on the detailed records of mud-reduction effect replacement, step-by-step pressurization, surface monitoring data, specific pressure relief time during the air-slurry replacement process, and mud-reduction effect injection volume to determine whether the conditions for entering the warehouse are met.

[0043] Embodiment 2:

[0044] The method for advancing a shield machine with pressure under the aid of the mud-reduction effect comprises the following steps:

[0045] Step 1: Calculate before entering the warehouse.

[0046] The stratum with stable ground and no buildings or pipelines on the ground is selected as the location for pressure entry. The pressure adjustment value considering different geological conditions, ground environment and excavation face position, and the sum of the head pressure calculated to the center of tunnel excavation are used as the theoretical working pressure of the excavation chamber air pressure operation. According to the calculated theoretical working pressure, field experiments are carried out to ensure that the theoretical working pressure meets the stability of the excavation face.

[0047] Step 2: Prepare membrane-building slurry.

[0048] The membrane-building mud adopts the gram mud effect. It includes main materials and auxiliary materials. The main materials include 85-99% calcium carbonate and 1-15% calcified fiber; the auxiliary materials include 50-80% water and 20-50% additives. The additives include one or more of plasticizers, thickeners, stabilizers, dispersants, and waterproofing agents; the main materials are added with 30-50% water by mass and mixed with the auxiliary materials in a mass ratio of 3:1.

[0049] Step 3: Water-stop seal ring.

[0050] The scope of the water stop ring is 3 to 7 rings of segments behind the shield tail. Bentonite is injected into the advance grouting holes, radial grouting holes and synchronous grouting holes of the shield machine in the order of the bottom of the shield machine-symmetrical waist-top, so that the bentonite fills the bottom gap and wraps the entire shield machine shell. Then, the grouting effect is injected in the same order, so that the grouting effect fills between the bentonite and the shield machine shell and evenly wraps the entire shield machine shell.

[0051] Step 4: Replace the slag with mud. There are three options:

[0052] Option 1: Inject the mud effect into the soil bin to replace the slag soil;

[0053] Option 2: Inject bentonite into the soil bin to replace the slag soil; then inject clay into the soil bin to replace the bentonite;

[0054] Option three: Inject bentonite into the soil bin to replace the slag soil; inject bentonite under pressure; inject Hengdun mud into the soil bin to replace bentonite; inject Ke Mud into the soil bin to replace Hengdun mud.

[0055] Before replacing the slag soil, the ground conditions should be investigated. For ground containing fine sand, medium-coarse sand and other ground that is prone to water loss and compaction, plan 2 should be used, and plan 3 should be used in serious cases; plan 1 should be used in other cases.

[0056] For Option 2, when injecting the clay effect into the soil bin to replace the bentonite, the soil bin pressure should be 0.2 bar higher than the pressure when the bentonite is injected into the soil bin.

[0057] For scheme 3, the pressure of pressurized injection of bentonite is 0.2~0.5 bar higher than the pressure when the bentonite is injected into the soil bin. The pressure of injecting Hengdun mud into the soil bin to replace the bentonite and injecting Ke Mud into the soil bin to replace Hengdun mud is increased by 0.2 bar respectively.

[0058] Step 5: Pressurize the mud.

[0059] After the slag is replaced in step 4, when the pressure is stable, a double-liquid mixed injection is performed using a special mud-effect grouting equipment, and step-by-step pressurization is performed directly.

[0060] The step-by-step pressurization uses 0.2 bar as a pressurization step. After each pressurization step, the pressure is appropriately reduced and stabilized until it reaches 1.5 times the working pressure of the warehouse. Taking the pressure of 1.6 bar after slag replacement as an example, the first pressurization is to 1.8 bar, and the injection of sludge effect is stopped. The pressure change of the soil warehouse is observed. If the pressure drops to 1.6 bar, sludge effect is added to make the soil warehouse pressure dynamically stabilized at slightly below 1.8 bar and maintained for 2 hours. After that, at the two pressurization levels of 1.8~2.0 bar and 2.0~2.2 bar, the pressure is also dynamically stabilized for 2 hours by adding sludge effect to a pressure slightly below the target pressure. The final pressurization level of 2.2~2.4 bar is dynamically stabilized for 6 hours.

[0061] During the dynamic injection of mud effect at each pressurized stage, the cutter disc is rotated half a circle at a low speed (0.1r / min) to ensure the uniformity of mud effect injection and penetration.

[0062] Step 6: Move the knife disc backward.

[0063] When the step-by-step pressurization in step 5 reaches the third-to-last level, i.e., 1.8~2.0 bar, loosen the hinge of the shield machine and use the reaction force of the injection pressure to move the shield machine back 3~5 cm. Fix the shield machine again and perform step-by-step pressurization. When the pressurization reaches the second-to-last level, i.e., 2.0~2.2 bar, loosen the hinge of the shield machine again and use the reaction force of the injection pressure to move the shield machine back 5~7 ​​cm. Increase the injection amount of the mud effect to fill the gap between the cutterhead and the excavation surface, forming a complete mud effect mud wall in front of the cutterhead.

[0064] Step 7: Gas displacement effect.

[0065] After a stable mud film is formed on the excavation surface, the automatic pressure-maintaining system of the sealed cabin is turned on and the pressure is maintained at the highest pressure for 6 hours. Then, natural pressure reduction is adopted first, and after the natural pressure reduction stops, the pressure is reduced to the working pressure by air release. When the air supply volume meets the requirements of the specification and the air pressure is stable, the screw conveyor is used to discharge the mud effect to reduce the liquid level of the mud effect in the bin.

[0066] Every time the liquid level of the sludge effect in the bin is reduced by 10-30%, the discharge of the sludge effect is stopped and the pressure is increased for the second time. The automatic pressure-maintaining system of the sealed cabin is turned on and the pressure is stabilized at the highest pressure for 1 hour. Then the pressure is reduced according to the same operation and the sludge effect is discharged again. During the pressure stabilization and pressure reduction process before discharging the sludge effect, the cutter head is rotated at a low speed (0.1r / min) to maintain the fluidity of the sludge effect slurry.

[0067] Step 8: Determine the conditions for entering the warehouse.

[0068] After replacing the gas with the mud effect, continue to open the automatic pressure-maintaining system until the working pressure in the warehouse can be stabilized and maintained for 6 hours, and the air compressor pressurization time is less than 10% of its standby time. Then it is judged that the mud film wall protection of the mud effect is completed, otherwise the mud film should be remade.

[0069] On-site engineers must conduct a comprehensive analysis and feedback on the detailed records of mud-reduction effect replacement, step-by-step pressurization, surface monitoring data, specific pressure relief time during the air-slurry replacement process, and mud-reduction effect injection volume to determine whether the conditions for entering the warehouse are met.

[0070] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for shield tunneling with pressure to enter a chamber with mud-killing effect, comprising the steps of: calculation before entering the chamber, preparation of membrane-building mud, water-stopping ring, replacement of slag with membrane-building mud, pressurization of membrane-building mud, retreat of the cutterhead, and replacement of membrane-building mud with gas, characterized in that: The membrane-building mud has the effect of reducing mud; The mud effect comprises a main material and auxiliary materials, wherein the main material comprises 85-99% calcium carbonate and 1-15% calcified fiber; the auxiliary materials comprise 50-80% water and 20-50% additives, wherein the additives comprise one or more of a plasticizer, a thickener, a stabilizer, a dispersant, and a waterproofing agent; after adding 30-50% water by weight to the main material, the auxiliary materials are mixed with the auxiliary materials in a mass ratio of 3:1; The water-stop seal ring is implemented at the 3rd to 7th ring of segments behind the shield tail, and the membrane-building mud is injected into the advance grouting holes, radial grouting holes and synchronous grouting holes of the shield machine body. The order of injecting the membrane-building mud is the bottom of the shield machine-symmetrical waist-top, forming a continuous water-stop ring; The membrane-building mud replacing the slag soil includes: injecting the membrane-building mud into the soil bin to replace the slag soil; When replacing the slag with the membrane-building slurry, grouting is performed through the reserved holes between the 10 and 2 points of the soil bin partition, and injected from the top; The continuous injection of the mud effect is achieved through a special grouting machine for the mud effect, so that stirring, mixing and injection are integrated.

2. The method for advancing a shield belt into a chamber with a mud-reducing effect according to claim 1 is characterized in that: Calculations before entering the warehouse include determining the theoretical working pressure, which is the sum of the pressure of geological conditions, ground environment and excavation face position and the head pressure at the center of tunnel excavation.

3. The method for pressing a shield belt into a chamber with a mud-reducing effect according to claim 1 is characterized in that: The membrane-building mud is pressurized in a stepped manner. When the pressure is stable after the slag is replaced, the membrane-building mud is injected and directly pressurized in a stepped manner.

4. The method for pressing a shield belt into a chamber with a mud-reducing effect according to claim 3 is characterized in that: The step-by-step pressurization takes 0.2 bar as one step, and the pressure is increased to 1.3~1.5 times of the working pressure entering the warehouse; each step of pressurization is continuously increased until the pressure is dynamically stable, and then the pressure is stabilized; during each step of pressurization, the cutter head of the shield machine is rotated half a circle at a low speed.

5. The method for pressing a shield belt into a chamber with a mud-reducing effect according to claim 4 is characterized in that: The cutterhead retreats by loosening the hinges or jacks of the shield machine when the step-by-step pressurization reaches the second-to-last stage, allowing the shield machine to retreat naturally under pressure, and maintaining pressure to inject membrane-building slurry to fill the gap between the cutterhead of the shield machine and the excavation surface.

6. The method for advancing a shield belt into a chamber with a mud-reducing effect according to claim 1 is characterized in that: The gas replacement membrane-building mud is implemented after the membrane-building mud forms a stable mud film on the excavation surface, including the following steps: opening the automatic pressure maintaining system of the sealed cabin, reducing the pressure to the working pressure after stabilizing the pressure for a period of time, discharging the membrane-building mud while replenishing air and maintaining the air pressure stable; and rotating the cutter head of the shield machine at a low speed while discharging the membrane-building mud.